Many earth moving vehicles use pressurized hydraulic fluid as a mechanism for performing work. For example, with a motor grader, an earth-engaging blade downwardly depending from a main frame may be lifted, rotated and tilted using hydraulic cylinders; while with an excavator, a boom arm may be articulated with first and second hinged arms and a bucket at the terminus thereof, each being associated with a hydraulic cylinder to effect movement. Another example is a loader, wherein a lift arm hinged to the loader has a rotatable bucket or other implement hinged to an end of the lift arm. A lift cylinder may be associated with the lift arm and a tilt cylinder may be associated with the bucket or implement. When it is desired to lift the arm, the hydraulic fluid is directed to the lift cylinder, and when it is desired to rotate the bucket or implement, hydraulic fluid may be directed to the tilt cylinder.
In order to control cylinders on each of the afore-mentioned vehicles and other hydraulically powered machines, hydraulic hoses are connected between the hydraulic pumps and the cylinders. The pumps are driven by the engine, typically diesel engine, of the earth moving vehicle. The hoses are typically reinforced hoses in that they have an inner elastomeric liner, a reinforcing layer surrounding the inner elastomeric layer, and an outer elastomeric cover surrounding the reinforcing layer. The elastomeric liner is flexible to enable motion between the cylinders and the pump and various moving parts on the earth moving vehicle. The liner is reinforced, typically with metallic wires or braids so as to be able to contain the significant pressures exerted by the hydraulic fluid being traversed therethrough. In addition, the elastomeric cover is provided around the reinforcing layer to protect the hose from ambient conditions, abrasions, and the environment.
Such hydraulic hoses terminate in couplings enabling the hose to be connected to the hydraulic pump, the hydraulic cylinder, or other elements needing hydraulic pressure provided on the earth moving vehicle. Typically, such couplings include an inner stem which is inserted into the inner diameter of the hydraulic hose, and a ferrule or outer shell extending from the stem and spaced concentrically from the stem to provide a hose receiving space therebetween. The ferrule is then crimped towards the stem to compress the hydraulic hose towards the stem and frictionally hold it in place. The distal end of the stem can terminate in any number of different configurations including a hexagonal threaded nut, a flared coupling, an angled coupling, a male coupling, a female coupling, or the like.
The aforementioned types of couplings are referred to as no-skive couplings in that the external layer of elastomeric material need not be removed prior to the attachment of the coupling. Rather the ferrule is in direct engagement with the outer elastomeric cover and through the use of sufficient teeth or serrations, a mechanical grip penetrates the elastomeric cover and engages the underlying reinforcing metallic layer. Alternatively, certain hydraulic hose couplings do in fact need to be skived, or in other words shaved, so as to remove the external elastomeric cover and expose the metallic reinforcing cover underneath. Only after the elastomeric cover is removed can such couplings then be mechanically coupled to the metallic layer. As such couplings require significant manual input, no-skive couplings have become the predominate player in the field of hydraulic hose couplings.
While effective, users and manufacturers of such equipment are continually seeking improvements. Two areas which are currently less than optimum are the retention strength of the couplings on the hydraulic hose, and the seal provided between the coupling and the hose. As can be imagined, such hoses and the terminating couplings are often subjected to severe operating environments, pulling forces, and rotational torques. The couplings need to be able to withstand such motions repeatedly and under severe conditions. Not only must the coupling remain attached to the hose to thereby continue to communicate hydraulic fluid, but it must do so with no leakage of the hydraulic fluid. Accordingly, the seal between the coupling and the underlying hydraulic hose must remain intact throughout its work cycle. Any leak can, at the very least, result in less than optimal performance of the earth moving vehicle, or more problematically, can result in failure of the machine entirely. This not only can result in lost productivity, but as the hydraulic fluid is under extreme pressures can present a safety concern as well.